QGIS API Documentation  2.18.3-Las Palmas (77b8c3d)
Public Member Functions | Protected Member Functions | Protected Attributes | List of all members
QgsVectorLayerDiagramProvider Class Reference

The QgsVectorLayerDiagramProvider class implements support for diagrams within the labeling engine. More...

#include <qgsvectorlayerdiagramprovider.h>

Inheritance diagram for QgsVectorLayerDiagramProvider:
Inheritance graph
[legend]

Public Member Functions

 QgsVectorLayerDiagramProvider (QgsVectorLayer *layer, bool ownFeatureLoop=true)
 Convenience constructor to initialize the provider from given vector layer. More...
 
 QgsVectorLayerDiagramProvider (const QgsDiagramLayerSettings *diagSettings, const QgsDiagramRendererV2 *diagRenderer, const QString &layerId, const QgsFields &fields, const QgsCoordinateReferenceSystem &crs, QgsAbstractFeatureSource *source, bool ownsSource)
 Construct diagram provider with all the necessary configuration parameters. More...
 
 ~QgsVectorLayerDiagramProvider ()
 Clean up. More...
 
virtual void drawLabel (QgsRenderContext &context, pal::LabelPosition *label) const override
 draw this label at the position determined by the labeling engine More...
 
virtual QList< QgsLabelFeature * > labelFeatures (QgsRenderContext &context) override
 Return list of label features (they are owned by the provider and thus deleted on its destruction) More...
 
virtual bool prepare (const QgsRenderContext &context, QStringList &attributeNames)
 Prepare for registration of features. More...
 
virtual void registerFeature (QgsFeature &feature, QgsRenderContext &context, QgsGeometry *obstacleGeometry=nullptr)
 Register a feature for labeling as one or more QgsLabelFeature objects stored into mFeatures. More...
 
- Public Member Functions inherited from QgsAbstractLabelProvider
 QgsAbstractLabelProvider (const QString &layerId=QString(), const QString &providerId=QString())
 Construct the provider with default values. More...
 
virtual ~QgsAbstractLabelProvider ()
 Vritual destructor. More...
 
Flags flags () const
 Flags associated with the provider. More...
 
QString layerId () const
 Returns ID of associated layer, or empty string if no layer is associated with the provider. More...
 
unsigned int linePlacementFlags () const
 For layers with linestring geometries - extra placement flags (or-ed combination of QgsPalLayerSettings::LinePlacementFlags) More...
 
QString name () const
 Name of the layer (for statistics, debugging etc.) - does not need to be unique. More...
 
QgsPalLayerSettings::ObstacleType obstacleType () const
 How the feature geometries will work as obstacles. More...
 
QgsPalLayerSettings::Placement placement () const
 What placement strategy to use for the labels. More...
 
double priority () const
 Default priority of labels (may be overridden by individual labels) More...
 
QString providerId () const
 Returns provider ID - useful in case there is more than one label provider within a layer (e.g. More...
 
void setEngine (const QgsLabelingEngineV2 *engine)
 Associate provider with a labeling engine (should be only called internally from QgsLabelingEngineV2) More...
 
virtual QList< QgsAbstractLabelProvider * > subProviders ()
 Return list of child providers - useful if the provider needs to put labels into more layers with different configuration. More...
 
QgsPalLayerSettings::UpsideDownLabels upsidedownLabels () const
 How to handle labels that would be upside down. More...
 

Protected Member Functions

void init ()
 initialization method - called from constructors More...
 
QgsLabelFeatureregisterDiagram (QgsFeature &feat, QgsRenderContext &context, QgsGeometry *obstacleGeometry=nullptr)
 helper method to register one diagram feautre More...
 

Protected Attributes

QgsDiagramRendererV2mDiagRenderer
 Diagram renderer instance (owned by mSettings) More...
 
QList< QgsLabelFeature * > mFeatures
 List of generated label features (owned by the provider) More...
 
QgsFields mFields
 Layer's fields. More...
 
QgsCoordinateReferenceSystem mLayerCrs
 Layer's CRS. More...
 
bool mOwnsSource
 Whether layer's feature source is owned. More...
 
QgsDiagramLayerSettings mSettings
 Diagram layer settings. More...
 
QgsAbstractFeatureSourcemSource
 Layer's feature source. More...
 
- Protected Attributes inherited from QgsAbstractLabelProvider
const QgsLabelingEngineV2mEngine
 Associated labeling engine. More...
 
Flags mFlags
 Flags altering drawing and registration of features. More...
 
QString mLayerId
 Associated layer's ID, if applicable. More...
 
unsigned int mLinePlacementFlags
 Extra placement flags for linestring geometries. More...
 
QString mName
 Name of the layer. More...
 
QgsPalLayerSettings::ObstacleType mObstacleType
 Type of the obstacle of feature geometries. More...
 
QgsPalLayerSettings::Placement mPlacement
 Placement strategy. More...
 
double mPriority
 Default priority of labels. More...
 
QString mProviderId
 Associated provider ID (one layer may have multiple providers, e.g. in rule-based labeling) More...
 
QgsPalLayerSettings::UpsideDownLabels mUpsidedownLabels
 How to handle labels that would be upside down. More...
 

Additional Inherited Members

- Public Types inherited from QgsAbstractLabelProvider
enum  Flag {
  DrawLabels = 1 << 1, DrawAllLabels = 1 << 2, MergeConnectedLines = 1 << 3, CentroidMustBeInside = 1 << 4,
  LabelPerFeaturePart = 1 << 6
}
 

Detailed Description

The QgsVectorLayerDiagramProvider class implements support for diagrams within the labeling engine.

Parameters for the diagrams are taken from the layer settings.

Note
added in QGIS 2.12
this class is not a part of public API yet. See notes in QgsLabelingEngineV2
not available in Python bindings

Definition at line 57 of file qgsvectorlayerdiagramprovider.h.

Constructor & Destructor Documentation

QgsVectorLayerDiagramProvider::QgsVectorLayerDiagramProvider ( QgsVectorLayer layer,
bool  ownFeatureLoop = true 
)
explicit

Convenience constructor to initialize the provider from given vector layer.

Definition at line 47 of file qgsvectorlayerdiagramprovider.cpp.

QgsVectorLayerDiagramProvider::QgsVectorLayerDiagramProvider ( const QgsDiagramLayerSettings diagSettings,
const QgsDiagramRendererV2 diagRenderer,
const QString layerId,
const QgsFields fields,
const QgsCoordinateReferenceSystem crs,
QgsAbstractFeatureSource source,
bool  ownsSource 
)

Construct diagram provider with all the necessary configuration parameters.

Definition at line 27 of file qgsvectorlayerdiagramprovider.cpp.

QgsVectorLayerDiagramProvider::~QgsVectorLayerDiagramProvider ( )

Clean up.

Definition at line 69 of file qgsvectorlayerdiagramprovider.cpp.

Member Function Documentation

void QgsVectorLayerDiagramProvider::drawLabel ( QgsRenderContext context,
pal::LabelPosition label 
) const
overridevirtual

draw this label at the position determined by the labeling engine

Implements QgsAbstractLabelProvider.

Definition at line 113 of file qgsvectorlayerdiagramprovider.cpp.

void QgsVectorLayerDiagramProvider::init ( )
protected

initialization method - called from constructors

Definition at line 60 of file qgsvectorlayerdiagramprovider.cpp.

QList< QgsLabelFeature * > QgsVectorLayerDiagramProvider::labelFeatures ( QgsRenderContext context)
overridevirtual

Return list of label features (they are owned by the provider and thus deleted on its destruction)

Implements QgsAbstractLabelProvider.

Definition at line 80 of file qgsvectorlayerdiagramprovider.cpp.

bool QgsVectorLayerDiagramProvider::prepare ( const QgsRenderContext context,
QStringList attributeNames 
)
virtual

Prepare for registration of features.

Must be called after provider has been added to engine (uses its map settings)

Parameters
contextrender context.
attributeNameslist of attribute names to which additional required attributes shall be added
Returns
Whether the preparation was successful - if not, the provider shall not be used

Definition at line 157 of file qgsvectorlayerdiagramprovider.cpp.

QgsLabelFeature * QgsVectorLayerDiagramProvider::registerDiagram ( QgsFeature feat,
QgsRenderContext context,
QgsGeometry obstacleGeometry = nullptr 
)
protected

helper method to register one diagram feautre

Definition at line 197 of file qgsvectorlayerdiagramprovider.cpp.

void QgsVectorLayerDiagramProvider::registerFeature ( QgsFeature feature,
QgsRenderContext context,
QgsGeometry obstacleGeometry = nullptr 
)
virtual

Register a feature for labeling as one or more QgsLabelFeature objects stored into mFeatures.

Parameters
featurefeature for diagram
contextrender context. The QgsExpressionContext contained within the render context must have already had the feature and fields sets prior to calling this method.
obstacleGeometryoptional obstacle geometry, if a different geometry to the feature's geometry should be used as an obstacle for labels (eg, if the feature has been rendered with an offset point symbol, the obstacle geometry should represent the bounds of the offset symbol). If not set, the feature's original geometry will be used as an obstacle for labels. Ownership of obstacleGeometry is transferred.

Definition at line 189 of file qgsvectorlayerdiagramprovider.cpp.

Member Data Documentation

QgsDiagramRendererV2* QgsVectorLayerDiagramProvider::mDiagRenderer
protected

Diagram renderer instance (owned by mSettings)

Definition at line 115 of file qgsvectorlayerdiagramprovider.h.

QList<QgsLabelFeature*> QgsVectorLayerDiagramProvider::mFeatures
protected

List of generated label features (owned by the provider)

Definition at line 129 of file qgsvectorlayerdiagramprovider.h.

QgsFields QgsVectorLayerDiagramProvider::mFields
protected

Layer's fields.

Definition at line 120 of file qgsvectorlayerdiagramprovider.h.

QgsCoordinateReferenceSystem QgsVectorLayerDiagramProvider::mLayerCrs
protected

Layer's CRS.

Definition at line 122 of file qgsvectorlayerdiagramprovider.h.

bool QgsVectorLayerDiagramProvider::mOwnsSource
protected

Whether layer's feature source is owned.

Definition at line 126 of file qgsvectorlayerdiagramprovider.h.

QgsDiagramLayerSettings QgsVectorLayerDiagramProvider::mSettings
protected

Diagram layer settings.

Definition at line 113 of file qgsvectorlayerdiagramprovider.h.

QgsAbstractFeatureSource* QgsVectorLayerDiagramProvider::mSource
protected

Layer's feature source.

Definition at line 124 of file qgsvectorlayerdiagramprovider.h.


The documentation for this class was generated from the following files: